Torsion damping device for a locking clutch, especially for a motor vehicle

ABSTRACT

A torsion device comprising an input part (20) comprising a piston (24) equipped with a guide washer (28) and an output part comprising an annular disc (36), and of the type comprising a series of lugs (44) folded radially inwards and which cooperate with the section (42) of a peripheral edge (40) of the disc (36). The edge (40) comprises a series of slots (48) distributed angularly like the lugs (44) of the first portion and dimensioned so as to allow the axial introduction of the lugs (44) into the slots (48) then the axial retention of the second portion (22) inside the first portion (20) by the relative rotation of these two portions by a fraction of a turn, in the manner of a bayonet-type mounting.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a torsion damping device for a lockingclutch capable of acting between the driving element and the drivenelement of a hydrokinetic coupling device, especially for a motorvehicle.

2. Description of the Prior Art

A locking clutch, usually known as a "LOCK-UP" clutch, for ahydrokinetic coupling device acting between a driving element and adriven element comprises a torsion damping device, a piston mountedmovably axially in relation to the driven element, at least one frictionlining associated with the piston and capable of being clamped betweenthe piston and a counter-piston.

The torsion damping device comprises an input part, called the firstportion, an output part, called the second portion, and springs placedcircumferentially between the input and output parts to couple themrotationally.

Such a clutch is for example described and represented in the documentsU.S. Pat. No. 4,875,562 and in International Patent ApplicationWO/FR93/00936 (WO94/07058).

In the document U.S. Pat. No. 4,875,562, the piston is adapted to formthe input part of the torsion damping device and it bears a frictionlining capable of coming into contact with the transversal wall of thehousing of the hydrokinetic device, this wall forming thecounter-piston.

The housing belongs to a tight case filled with oil and it is capable ofbeing connected rotationally to a driving shaft.

The output part of the damping device is integral with the turbine wheelof the hydrokinetic device.

The turbine wheel is integral with a hub capable of being rotationallyconnected to a driven shaft.

Thus, the case forms a driving element whereas the hub of the turbinewheel forms a driven element and the locking clutch is capable of actingbetween the case and the turbine wheel to perform a couplingtherebetween.

In the document U.S. Pat. No. 4,875,562, the torsion damping devicecomprises the piston externally retaining the springs (or resilientmembers), and also a guide washer borne by being fixed, in this case byriveting, by the piston and which internally retains the springs thanksto retention lugs.

The piston and the guide washer have bearing lugs to act on thecircumferential ends of the springs. On its outer periphery the pistonalso has a cylindrical annular skirt.

The input portion is thus formed by two parts, whereas the outputportion comprises an annular disc which is integral with the turbinewheel.

The output disc has bearing lugs, which penetrate between thecircumferential ends of two consecutive springs to act thereon.

These lugs each penetrate radially between two bearing lugs associatedwith the piston and the guide washer respectively.

In the document WO94/07058, the torsion damping device comprises twoparts, with the guide washer being fixed on the piston. This guidewasher and the disc have retention parts for retaining the springsexternally and internally respectively.

Furthermore, the disc and the guide washer have bearing lugs for actingon the circumferential ends of the springs.

As described and represented in this document WO94/07058, means arespecified to initially axially retain the disc inside the first portionand to allow a relative angular clearance between the two portions ofthe damping device, which comprise a series of snap-on lugs of the guidewasher of the first portion which are folded radially inwardly in thedirection of the axis of the damping device and which cooperate with thesection of a cylindrical annular peripheral edge of the disc of thesecond portion.

Thanks to these retention means, after mounting the springs, by snappingthe disc into the snap-on lugs, it is possible to create a sub-assemblywhich is unitary, captive, easy to handle and transportable, compilingthe piston and the torsion damping device, this sub-assembly being thenable to be positioned on the turbine hub.

Although the assembly of the disc with the washer by snapping betweenthe folded parts is facilitated by the fact that the washer is lessthick than the disc, it is not entirely satisfactory insofar as itcomplicates the production of the washer and insofar as this type ofassembly by interlocking, which calls on a momentary deformation of thesnap-on and retention lugs, results in a not negligible force beingdeveloped during assembly by interlocking.

SUMMARY OF THE INVENTION

The object of the present invention is to propose a new design of atorsion damping device comprising, in a simple and economical manner,improved means for the axial retention of the disc of the second portionof the damping device in relation to the first portion of the latter.

To this end, the invention proposes a torsion damping device of the typementioned above, characterised in that the annular peripheral edge ofthe disc comprises a series of slots distributed angularly like the lugsof the first portion and dimensioned so as to allow the axialintroduction of the lugs into the slots then the axial retention of thesecond portion inside the first portion by relative rotation of thesetwo portions by a fraction of a turn, in the manner of a assembly of thebayonet type and in that the said lugs are formed in a cylindricalannular skirt which the piston has on its outer periphery.

Thanks to the invention, the guide washer is simplified and the assemblyforce is reduced since the lugs only have to be deformed momentarily.Moreover the guide washer - piston assembly is very rigid.

According to other advantages of the invention:

the lugs and the slots are arranged in series of pairs of adjacent lugsand slots;

the piston externally retains the springs and thus belongs to thetorsion damping device. Thanks thereto bosses can be produced in advancein the disc for bearing the springs and the guide washer is furthersimplified.

The disc advantageously comprises openings to finally allow theattachment by riveting of the guide washer to the piston and theformation of a sub-assembly.

Other characteristics and advantages of the invention will becomeapparent from reading the following detailed description, for theunderstanding of which reference will be made to the attached drawingsin which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a right-hand lateral view, along arrow F1 of FIG. 2, of themain components of a damping device produced in accordance with theteachings of the invention;

FIG. 2 is a partial sectional view along line 2--2 of FIG. 1; and

FIG. 3 is a perspective view of a detail on a larger scale illustratingthe design of the retention lugs of the disc.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The housing 10 of a torque converter (not represented) equipped with atorsion damping device 12 produced in accordance with the teachings ofthe invention is represented in silhouette on FIG. 2.

The housing 10, which has an annular shape, comprises an end wall 14,generally transversally orientated, in the form of a disc and acylindrical annular skirt 16, generally axially orientated, extending tothe outer periphery of the wall 14.

The wall 14 is planned to be connected to a primary shaft or drivingshaft, whereas the skirt 16 is planned to be fixed to the outer edge ofa impeller wheel (not represented) of the converter, as described indocument WO94/07058, to form a tight case filled with oil.

A turbine wheel 18 of the converter, which is planned to be fixed to anoutput shaft or driven shaft, has also been represented in silhouette onFIG. 2. The converter also comprises a reaction wheel (not visible).

The torsion damping device 12 is disposed between the wall 14 of thehousing 10 and the turbine wheel 18 and comprises a first portion 20,forming an input part, and a second portion 22, forming an output part,which are coaxial and capable of rotating in relation to one another inopposition to circumferentially acting resilient means, here precurvedcoil springs 30, and of moving axially in relation to one another. Thesprings 30 are disposed on the outer periphery of the housing 10 and ofthe turbine wheel 18.

Reference can be made to the contents of the two previously mentioneddocuments to learn in detail of the arrangement of the variouscomponents of the torsion damping device and their connections with thecomponents of the torque converter.

The first portion 20 is essentially formed of a piston 24 in the form ofan annular disc which extends adjacently to the wall 14 of the housing10 and which is extended at its outer periphery by an axially orientedcylindrical annular skirt 26.

On its outer face, faced towards the wall 14, the piston 24 bears byfixing a friction lining 60 intended to be clamped against the wall 14.

Of course as a variant the lining 60 may be integral with the wall 14.

On its inner face, faced towards the turbine wheel 18, the piston 24 isequipped with a guide washer 28 of the springs 30, which is fixedthereto by a series of circumferentially distributed rivets 32.

According to a known design, the washer 28 comprises fittings 34 orparts 34 for the support of the circumferential ends of the springs 30.

The second portion 22 of the torsion damping device 12 is essentiallyformed by a plate in the shape of an annular disc 36, which alsocomprises parts 38 serving as a support for the circumferential ends ofthe springs 30.

The disc 36 is extended at its outer periphery towards the wheel 18, inthe opposite direction to the piston 24, by an annular cylindricalannular edge 40, which, like the skirt 26 of the piston 24, is axiallyorientated and which is slidingly received inside the latter.

The axially orientated cylindrical annular edge 40 ends in an annularend section 42. The piston 24 is thicker than the guide washer 28 andthan the disc 36.

More precisely, the guide washer 28, here metallic, has on its outerperiphery parts 34 with a U-shaped section inserted between twoconsecutive springs 30. The circumferential ends of the springs 30 bear,possibly indirectly by means of bearing plates, on the section of theparts 34 axially directed towards the turbine wheel 18 and the disc 36.

Thus two axially oriented bearing lugs are defined by part 34, with thelonger one serving for the external bearing of the springs 30 and theother one, which is shorter axially, for the internal bearing of thesprings 30. This short lug is obtained by blanking and folding from theguide washer 28. The long lug is slidingly received inside the skirt 26.

The disc 36, here metallic, has the above-mentioned parts 38 penetratingradially between the lugs of the parts 34. More precisely the bearingparts 38 of the ends of the springs 30 are formed by means of bearingbosses in a sinuous shape extending to the outer periphery of the disc36 formed to retain the springs 30 internally.

This outer periphery having bearing bosses 38 here is in a demi-shell ordemi-toric shape to retain internally the springs 30. It is extended atits outer periphery by the annular edge 40 protruding axially towardsthe turbine wheel 18.

The piston 24, here metallic, thanks to its skirt 26 allows the springs30 to be externally retained. This skirt 26 surrounds the disc 36, whichis radially extended towards the interior by a generally axiallyorientated flange, provided on its inner periphery with a hub for itsrotational connection with the hub of the turbine wheel as described indocument WO94/07058.

In accordance with the invention, the axial retention of the secondportion 22 of the torsion damping device 12 inside the first portion 20is ensured by means of a series of pairs of retention lugs 44 formedintegrally by blanking and bending in the thinner portion of the freeend 46 of the cylindrical annular skirt 26 of the piston 24.

In the embodiment illustrated on the figures, the retention lugs 44,which beforehand are folded radially towards the inside, number sixarranged in three pairs of adjacent lugs and are angularly distributedin a regular manner in pairs as can be seen on FIG. 1.

In order to allow the axial introduction of the disc 22 to the inside ofthe first portion 20, the annular peripheral edge 40 of the lattercomprises three series of introduction slots arranged in pairs 48.

The introduction slots 48 are distributed regularly in the same manneras the retention lugs 46 and circumferentially they have dimensions soas to allow the passage of the lugs 44 into the slots 48 to bring theannular section 42 of the peripheral edge 40 of the disc 36 set backfrom the radial plane delimited by the inner face 50 of the retentionlugs 44, then to allow, according to the invention, a relative rotationof the two portions 20 and 22 to bring, as illustrated in FIGS. 1 and 2,the radially oriented retention lugs 44 opposite the parts of thesection 42 not having slots 48. The slots 48 are wider circumferentiallythan the lugs 44 for ease of assembly. They are easily obtained bystamping or cutting.

The arrangement and the dimensioning of the retention lugs 44 and of theslots 48 thus allow the bayonet-type mounting enabling the assembly ofthe first and second portions 20 and 22 of the torsion damping device 12to be produced without causing elastic deformation of the lugs and witha reduced assembly force.

More precisely, on its inner periphery the guide washer 28 hasattachment lugs 128 directed towards the axis of the assembly and thepiston 36 has longer circumferential openings opposite the lugs 128.

Thus the guide washer 28 can be riveted to the piston 24, three rivets32 being provided per lug 128. Thanks thereto, an assembly comprisingpiston 24, washer 28, springs 30, disc 36 which is unitary, captive,easy to handle and transportable is produced.

Thus the springs 30 are advantageously placed on the fittings 34 of theguide washer 28, then the bosses 38 of the disc 36 are mounted betweenthe circumferential ends of the springs 30, then the assembly comprisingthe guide washer 28, the springs 30 and the disc 36 is mounted in thepiston 24 by engaging the lugs 44 in the slots 48, finally the guidewasher 28 - disc 36 assembly is rotated to proceed with riveting at 32of the washer 28 on the piston 24 thanks to the lugs 128 and to thecorresponding openings 228.

Thus the lugs 44 can be hot-bent or cold-bent beforehand.

It is apparent from the evidence of the description and of the drawingsthat the openings 228 finally allow the attachment of the guide washer28 and the formation of the above-mentioned sub-assembly.

Of course after assembly the circumferential distance between the lugs44 and the slots 48 depends on the applications, especially the relativeangular clearance between the disc 36 and the piston 24.

Thanks to the retention of the springs 30 by the piston 24, the bosses38 of the disc 36 can be produced in advance and the guide washer 28 canbe simplified.

As a reminder, it will be recalled that during operation the piston 24may move axially under the effect of the difference in hydraulicpressure existing on either side of its faces. Thus the friction lining60 may be clamped or not between the wall and the piston 24.

In the first case the locking clutch, comprising the piston 24 and thedamping device 12, is locked with rotational connection between thehousing 10 and the hub of the turbine wheel 18 in order to limitslippage.

Of course, the invention is not limited to the embodiment which has justbeen described.

The invention also includes all embodiments of the type enabling abayonet-type axial connection to be provided, i.e. the systems achievinglocking by a fraction of a turn.

Of course, the inner periphery of the guide washer 28 may be continuousand not divided into lugs 128. The washer 28 therefore has a zone forattachment at its inner periphery.

As a variant, the free end 46 of the skirt 26 of the piston 24 may havea constant thickness, the lugs 44 having the same thickness as the saidskirt 26, depending on the applications.

As a variant, the guide washer 28 may externally retain the springs 30as in document WO 94/07058, but this complicates production.

We claim:
 1. A torsion damping device (12) for a locking clutch capable of acting between a housing (10) and a turbine wheel of a hydrokinetic coupling device, said torsion damping device comprising: two coaxial portions (20, 22), mounted movably in relation to one another in opposition to circumferentially acting springs (30), among which an input part (20) defined by a first portion having a piston (24) equipped with a guide washer (28) for bearing the springs (30), which is fixed thereto by riveting, and an output part defined by a second portion having an annular bearing disc (36) for the springs (30), and means for axially retaining the annular bearing disc (36) inside the first portion (20), thereby allowing a relative angular clearance between the first and second portions (20, 22), which comprise a series of lugs (44) of the first portion folded radially inwardly cooperatively with a section (42) of a cylindrical annular peripheral edge (40) of the disc (36) of the second portion (22), wherein the cylindrical annular peripheral edge (40) of the disc (36) comprises a series of slots (48) distributed angularly like the lugs (44) of the first portion and dimensioned so as to allow axial introduction of the lugs (44) into the slots (48) and axial retention of the second portion (22) inside the first portion (20) by relative rotation of the first and second portions by a fraction of a turn, in the manner of a bayonet-type mounting, and said lugs (44) are formed in a cylindrical annular skirt (26) which the piston (24) has on its outer periphery.
 2. A torsion damping device according to claim 1, wherein the lugs (44) and the slots (48) are arranged in series of pairs of adjacent lugs (44) and slots (48).
 3. A torsion damping device according to claim 2, wherein the piston (24) externally retains the springs (30), and the disc (36) internally retains the springs (30).
 4. A torsion damping device according to claim 3, the guide washer (28) has a zone disposed on an inner periphery for attachment by riveting to the piston (24), and the disc (36) has openings (228) to allow attachment of the guide washer (28) to the piston (24) by riveting.
 5. A torsion damping device according to claim 4, wherein the guide washer (28) has attachment lugs (128) disposed on an inner periphery thereof opposite the openings (228).
 6. A torsion damping device according to claim 1, wherein the lugs (44) have a reduced thickness in relation to the annular skirt (26) of the piston (24).
 7. A torsion damping device according to claim 1, wherein the cylindrical annular peripheral edge (40) of the disc (36) is slidingly received in the interior of the cylindrical annular skirt (26) of the piston (24). 